The ornamental design for a portion of a vehiclegrille, as shown and described.
FIG. 1 is a perspective view of a portion of a vehicle grille showing the new design;
FIG. 2 is front elevational view thereof; and,
FIG. 3 is a right side elevational view thereof, a left side elevational view thereof being a mirror image of the right side elevational view.
The top view, bottom view and rear view of the portion of a vehicle grille not shown are disclaimed. The broken line portion showing the remainder of the vehicle grill is for illustrative purposes only and forms no part of the claimed design.